`
https://leetcode.cn/problems/element-appearing-more-than-25-in-sorted-array/
`

/**
 * @param {number[]} arr
 * @return {number}
 */
var findSpecialInteger = function (arr) {
  // 思路：https://leetcode.cn/problems/element-appearing-more-than-25-in-sorted-array/solutions/3067559/olog-n-er-fen-cha-zhao-zheng-que-xing-zh-5mu9/
  const m = Math.floor(arr.length / 4)
  for (let i = m; i <= m * 2; i++) {
    const x = arr[i]
    const j = _.sortedIndex(arr, x)
    if (arr[j + m] === x) return x
  }
  return arr[m * 3 + 2]
};